Matsushita Electric Industrial Co., Ltd.

Matsushita Electronics Corporation

Katsuya Ishikawa

Atsuhisa Kageyama

Takao Kuroda

Hidetoshi Suzuki

Hisao Kunitani

Keiichi Ito

Yuji Matsuda

Masahiko Niwayama

Sumio Terakawa

Keishi Tachikawa

Yuki Kakuya

Shigeru Okamoto

Nobutaka Okada

The present invention has an object to provide a gradation correcting apparatus for correcting the gradation of the white side of a video luminance signal. The gradation correcting apparatus is provided with a maximum value detectorfor detecting a maximum value of a luminance signal S, a white comparatorfor comparing the luminance signal S, a maximum luminance value Sdetected by the maximum value detector, and a first white threshold value S, a white linear converterfor performing linear conversion on the luminance signal Son the basis of the maximum luminance value S, the first white threshold value S, and a second white threshold value S, and a white controllerfor correcting the luminance signal Son the basis of the result of the comparison in the white comparator, the output of the white linear converter, and the second white threshold value S

Gradation correcting apparatus gradation correcting method and video display apparatus

An object of the present invention is to provide a signal processor which improves the offset accuracy of a video signal without increasing the number of bits of a circuit. An N-bit adder () adds a video signal (S) and an upper-N-bit signal of a brightness control signal (S) as an offset value. A 1-bit pulse generator () generates a 1-bit pulse signal (S) in which '1' and '0' have equal chances of appearing at random. A selector () selects the 1-bit pulse signal (S) when the LSB of the brightness control signal (S) is &#x201c;1&#x201d;, while selects a ground level &#x201c;0&#x201d; when the LSB is &#x201c;0&#x201d;, and supplies the selected signal to a carry input of the N-bit adder ().

Signal processor

A gradation correction circuit comprises: an arithmetic means ( ) for operating an output value corresponding to each broken point of a broken line in a vertical blanking period; a level detection circuit for identifying a size relation between each broken line point which is an input value corresponding to each broken point and an input video signal, and calculating a difference between the input video signal and each broken line point; and a correction means ( ) for selecting a gradient of the broken line on the basis of the result identified by the level detection circuit , and performing gradation correction of the input video signal on the basis of the selected gradient of the broken line, the output value calculated by the arithmetic means, and the difference calculated by the level detection circuit, wherein the arithmetic means and the correction means share a number of circuits ( ). Therefore, there is provided a gradation correction circuit where video correction with high precision can be realized without using a memory storing a lookup table, or without increasing a circuit scale.

Gradation correction circuit, and &ggr; correction apparatus

An appropriate correction quantity is obtained for a video luminance signal on an individual video basis with a characteristic value, like the maximum or average value, of the luminance signal taken into account, thereby performing gray scale correction more effectively. A dynamic gamma correction apparatus for performing a correction on a video luminance signal includes: a correction start point control section for obtaining a correction start point, which is a lower limit of a given correction range, in accordance with a characteristic value of the luminance signal; a gamma correction quantity calculating section for obtaining a provisional correction quantity for the luminance signal to be corrected using the correction start point and the luminance signal; a gamma correction gain control section for obtaining a gain for the provisional correction quantity in accordance with the characteristic value of the luminance signal; a multiplier for obtaining a product of the provisional correction quantity and the gain as a gamma correction quantity; and an adder for obtaining a sum of the luminance signal and the gamma correction quantity and outputting the sum. The correction start point and the gain for the provisional correction quantity are controllable in accordance with the characteristic value of the luminance signal. Thus, an appropriate gamma correction quantity can be obtained as a final correction quantity.

Dynamic gamma correction apparatus

The present invention provides a color difference signal correction apparatus for correcting color difference of parts having no color, particularly white characters, which can make the correction with high accuracy also for images including lightly colored parts. The color difference signal correction apparatus of the present invention comprises a full-wave rectification circuit for full-wave rectifying an input color difference signal (R&minus;Y)a, a full-wave rectification circuit for full-wave rectifying an input color difference signal (B&minus;Y)b, an addition circuit for adding the outputs of the full-wave rectification circuit and the full-wave rectification circuit , an addition circuit for adding a white character slice level signal e and the output of the addition circuit , a luminance signal slice circuit for slicing a luminance signal g with the output of the addition circuit , and an addition circuit for adding the output of the luminance signal slice circuit and the input color difference signal (B&minus;Y)b and outputting the addition result.

Color difference signal correction apparatus

A solid-state image pick-up device having a structure in which the amount of transferred charges is not reduced in a vertical CCD portion even if a pixel portion is made finer, and a method for manufacturing the solid-state image pick-up device are provided. A first p-type well and a second p-type well are formed on an N (100) silicon substrate. A vertical CCD n.sup.+ layer is formed in the second p-type well 3. Then, impurity ions are implanted into a surface layer of the N (100) silicon substrate including an upper layer portion of the vertical CCD n.sup.+ layer to form a p.sup.- layer. An isolating portion for isolating photodiode portions from the vertical CCD n.sup.+ layer and a read control portion for controlling the read of charges from the photodiode n layer are simultaneously formed on a portion adjacent to the vertical CCD n.sup.+ layer.

Solid-state image pick-up device and method for manufacturing the same

The impurity density of a photoelectric transducer n-layer (7) and the impurity density of a p-layer ( 6 ) of an impurity region in which the electric transducer (7) and a transfer channel (9) are formed, are each distributed to have its maximum value in a more interior part from the surface of a semiconductor substrate (5). Alternatively, i) a thin, high-density p-layer (34) and ii) a thick, low-density p-layer (33) of an impurity region in which the electric transducer (7) and the transfer channel (9 ) are formed may be formed. Each minimum potential in these two p-layers (33, 34) is made to have a different dependence on the voltage applied to an n-type semiconductor substrate ( 5). The thick, low-density p-layer ( 33 ) is formed in such a way that it comes into contact with part of the photoelectric transducer n-layer (7) at its bottom portion. The above constitution can bring about a solid-state image pickup device that can prevent the blooming phenomenon, causes less residual images, and can operate as an electronic shutter with ease.

Process for manufacturing a solid state image pickup device having

The impurity density of a photoelectric transducer n-layer (7) and the impurity density of a p-layer (6) of an impurity region in which the electric transducer (7) and a transfer channel (9) are formed, are each distributed to have its maximum value in a more interior part from the surface of a semiconductor substrate (5). Alternatively, i) a thin, high-density p-layer (34) and ii) a thick, low-density p-layer (33) of an impurity region in which the electric transducer (7) and the transfer channel (9) are formed may be formed. Each minimum potential in these two p-layers (33, 34) is made to have a different dependence on the voltage applied to an n-type semiconductor substrate (5). The thick, low-density p-layer (33) is formed in such a way that it comes into contact with part of the photoelectric transducer n-layer (7) at its bottom portion. The above constitution can bring about a solid-state image pickup device that can prevent the blooming phenomenon, causes less residual images, and can operate as an electronic shutter with ease.

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Takatsuki, Japan

Katsuya Ishikawa